Conventionally, in the manufacture of semiconductor devices, micro-processing by lithography using a photoresist has been carried out. The micro-processing is a processing method including forming a thin film of a photoresist on a semiconductor substrate such as a silicon wafer, irradiating the photoresist with active rays such as ultraviolet rays through a mask pattern in which a pattern for a semiconductor device is depicted, developing the photoresist to obtain a photoresist pattern, and etching the substrate using the obtained photoresist pattern as a protective film, thereby forming fine unevenness corresponding to the pattern on the surface of the substrate. In recent progress in high integration of semiconductor devices, shorter wavelength active rays tend to be used, i.e., an ArF excimer laser (193 nm) and EUV light (13.5 nm) have been taking the place of a KrF excimer laser (248 nm).
This tendency requires more precise control of the profile (resist shape) and higher level of adherence to the substrate than before.
A film known as a hard mask that contains a metal element such as silicon is used as an underlayer film between a semiconductor substrate and a photoresist. In this case, the resist and the hard mask significantly differ in the components, which makes the rate at which the resist and the hard mask are removed by dry etching highly dependent on the type of the gas used in the dry etching. Appropriate selection of the type of the gas allows the hard mask to be removed by dry etching without significant reduction in the film thickness of the photoresist. A resist underlayer film has been thus disposed between a semiconductor substrate and a photoresist in order to achieve various effects in the ‘manufacture of semiconductor devices in recent years (see Patent Documents 1 and 2).
Although compositions for a resist underlayer film have been studied, development of a novel material for a resist underlayer film is demanded to meet diverse properties that the resist underlayer film is required to have.